1. Field of the Invention
The invention relates to a process for the stabilization of dusting surfaces with polymers in form of water-redispersible polymer powders, which are optionally reemulsifiable modified, or reemulsifiable modified aqueous polymer dispersions.
2. Background Art
Dust control and soil stabilization is a major environmental and health issue. Dust, for example road dust of unpaved roads and gravel roads, pollutes the environment and poses health risks. Soil stabilization retards both wind and water erosion. Furthermore the condition of roads is an important part of road safety. It is improved by the stabilization of unpaved roads preventing the development of ruts, bumps and washboards. Fine particle stabilization also has significant economic advantages in extending the working lives of such machinery as air heating and cooling units and turbine engines. In general dust is composed of fine particles with a particle size of 1 μm to 2 mm.
For soil stabilization it has been the state of art to spray mineral oil products onto the surface of unpaved roads with all the environmental disadvantages. Water-dilatable binders like calcium chloride solutions and lignosulfonate solutions have also been used for dust control and surface stabilization. JP-B 05-53881, ZA-A 8803253, and JP-B 49046716 concern surface stabilization with conventional aqueous polymer dispersions. Aqueous polymer solutions, e.g. solutions of polyacrylic acid have been used to control dust on gravel roads. The major problem of water based polymer products is that 1) they only bind dusting particles a single time because they do not redisperse, 2) they are slow to dry and form films due to the water necessary to apply the dispersions and 3) they are more difficult to till or scarify into the material being bound due to their inherent liquid state. Therefore every half year these compounds have to be applied again. When used in deep reaching applications (i.e. depths of more than one inch) to improve durability, water based products show the additional disadvantage of drying much too slowly, which leads to prohibitive closure times of the road. Considering the above mentioned rate of erosion and the subsequent frequent rate of application, the state of the art is not only economically disadvantageous but also environmentally questionable considering the biodegradability and the chemical nature of most monomer bases now in use for this type of application.
U.S. Pat. No. 3,736,758 discloses a process for rendering soil at chemical storage sites impervious to liquids, by adding a conventional polymer dispersion to a depth of soil, moistening and compacting the soil, and applying an impermeable thick film or coating of an organic polymer over the treated and compacted soil to render the surface impermeable. The process is expensive due to the amount of impermeable polymer added onto the surface, and for many such polymers requires an organic solvent which is environmentally undesirable. If the integrity of the stabilized soil is compromised, the soil cannot be again stabilized without removing the impermeable coating and adding additional polymer dispersion.